How to Turn On Spell Checker in Microsoft Word

Spell checker is one of those features most people assume is always running — until they notice a document full of uncaught typos. Whether it stopped working, was disabled at some point, or never seemed to activate in the first place, getting it back on is usually straightforward. But the exact steps depend on which version of Word you're using, what settings have been changed, and whether the issue is with one document or your entire installation.

What Spell Checker Actually Does in Word

Microsoft Word uses two related tools that often get grouped together: spell check and grammar check. Spell check flags words that don't match its dictionary. Grammar check catches sentence-level issues like subject-verb agreement or passive voice. Both run automatically in most configurations, underlining errors with colored squiggly lines — red for spelling, blue or green for grammar, depending on your version.

These features rely on a proofing language being set correctly. If Word doesn't know what language a passage is written in, it can't check it against the right dictionary. This is one of the most common — and most overlooked — reasons spell check appears broken.

How to Turn On Spell Check in Word (Step by Step)

In Word for Windows (Microsoft 365 / Word 2016, 2019, 2021)

1. Open Word and go to File → Options
2. Select Proofing from the left sidebar
3. Under When correcting spelling and grammar in Word, make sure these boxes are checked:
   • ✅ Check spelling as you type
   • ✅ Mark grammar errors as you type
   • ✅ Check grammar with spelling
4. Click OK

If those boxes were already checked, scroll down to check whether "Hide spelling errors in this document only" or "Hide grammar errors in this document only" are ticked — these suppress the underlines for the current file without disabling the feature globally.

In Word for Mac (Microsoft 365 / Word 2016 and later)

1. Open Word and go to Word → Preferences from the menu bar
2. Click Spelling & Grammar
3. Enable Check spelling as you type and Check grammar as you type
4. Close the preferences window

The layout is slightly different from Windows but the logic is the same.

In Word Online (Browser Version)

Word Online has a more limited proofing toolset. Basic spell check runs automatically and can be toggled under Review → Spelling & Grammar. Grammar suggestions may be more limited compared to the desktop app, depending on your Microsoft 365 subscription tier.

Why Spell Check Gets Turned Off (Common Causes)

Understanding what disables spell check helps prevent it from happening again:

The "Do not check spelling or grammar" flag is worth special attention. It can be applied to selected text — so if you paste content from another source, it may carry that flag with it. Even with spell check fully enabled globally, that text won't be checked until the flag is removed.

The Role of Proofing Language 🌐

If spell check is on but still not catching errors, the proofing language is the first thing to investigate. Word needs to know whether to check against American English, British English, French, Spanish, or any other supported language.

To check and set it:

1. Select all text (Ctrl+A on Windows, Cmd+A on Mac)
2. Go to Review → Language → Set Proofing Language
3. Choose the correct language and confirm "Do not check spelling or grammar" is unchecked
4. Click OK and run spell check again

This single step resolves a large portion of spell check problems, especially in documents that were shared between users in different regions or created from templates.

Running Spell Check Manually

If you prefer not to use the real-time underline feature, you can run spell check manually at any time:

• Press F7 (Windows and Mac)
• Or go to Review → Spelling & Grammar

This opens the proofing pane and walks through each flagged issue one at a time. Some users prefer this approach to avoid distracting underlines while drafting.

When Spell Check Works Globally But Misses Specific Words ✏️

Word's dictionary won't flag words it recognizes — even if they're used incorrectly. Correctly spelled wrong words (like "their" vs. "there," or "form" vs. "from") are a grammar and context problem, not a spelling problem. The grammar checker handles some of these, but its accuracy varies depending on sentence complexity and your Word version.

You can also add words to your Custom Dictionary — useful for technical terms, names, or industry-specific vocabulary that would otherwise show as errors constantly.

Variables That Shape Your Experience

How spell check behaves isn't uniform across every setup. A few factors meaningfully change the experience:

• Subscription vs. standalone license — Microsoft 365 subscribers tend to get more frequent updates to the grammar engine and AI-assisted suggestions like Editor
• Desktop vs. web vs. mobile — The full feature set lives in the desktop app; Word Online and the mobile apps have scaled-down proofing tools
• Document origin — Files from older Word versions, PDFs converted to Word, or content pasted from web sources often carry formatting and language flags that interfere with proofing
• IT-managed installations — In corporate environments, some proofing settings may be controlled by group policy, meaning individual users can't change them regardless of what they see in the options menu

Whether the steps above fully resolve things — or whether something deeper like a corrupted template or managed policy is involved — depends on the specific environment the document lives in.